Dilatation and stent delivery system and related methods

ABSTRACT

The invention relates to a system for dilatation of a body passage and delivery of a stent into the body passage of a patient, and related methods of using such a system. The dilatation and stent delivery system may comprise a dilatation catheter having an expandable member on a distal end, and a stent delivery catheter configured to retain a stent and deliver the stent to a body passage. The stent delivery catheter defines a lumen sized to receive the dilatation catheter and permit movement of the dilatation catheter relative to the stent delivery catheter.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a system for dilatation of a bodypassage and delivery of a stent into the body passage of a patient, andrelated methods of using such a system.

2. Description of Related Art

Stents are well-known endoprotheses. A conventional endoprosthetic stentincludes a radially-expandable, tubular structure. The tubular structurecan expand radially from a compact form for delivery to an expanded formfor implantation. Radial expansion of the stent effects implantationinto the tissue of a body passage wall being repaired, supported, orbridged. The body passage can include, for example, a body canal, bloodvessel, duct, other passage, and the like.

A conventional endoprosthetic stent can be mechanically expansive orself-expansive. A conventional mechanically-expansive stent initiallypossesses a radially compact form. The stent is loaded onto a deliverysystem, such as a catheter. Typically, an expandable balloon ispositioned in the tubular structure of the stent. After delivering thestent to the region of a body passage being repaired or bridged, theballoon is expanded, thereby implanting the stent onto the passage wall.To expand the stent, the balloon must be connected to a fluid source bymeans of a lumen or some other tubular structure.

A conventional self-expansive stent initially possesses aradially-expanded form. The stent is compressed radially as it isassembled onto a delivery system. Typically, an outer tubular structureretains the compressed stent until it is delivered to the region of apassage being repaired or bridged. The stent is then released from itscompressed state and self-expands to implant onto the passage wall. Anexpandable balloon is not required to expand the stent. However, incases where a stricture of the passage is difficult to repair or bridge,a physician may use a balloon to assist with expansion of the deployedstent.

Generally, when a balloon is used to assist with expansion of aself-expanding stent, the conventional stent delivery system is removedafter the stent is successfully deployed. Then, either a separatesingle-use balloon catheter or a second delivery system having anexpandable balloon is delivered to the site of the stent. In eitherevent, a physician would be slowed by this process of removing the stentdelivery system and delivering the balloon.

Conventional stent delivery systems generally include a minimaltransverse dimension so that a distal end of the delivery system can benavigated through and along a patient's lumens, either in a percutaneousinsertion procedure, through the working channel of an endoscope orlaparoscope, or next to a scope. Often times, physicians use a deliverysystem in combination with a medical guide wire. Typically, intransluminal procedures, the physician directs a guide wire throughnarrow passages in a patient's body using a steering mechanism providedat a proximal end outside of the body. The physician monitors the traveland position of a distal end of the guide wire by a fluoroscope or otherknown method or device. Once the distal end of the guide wire reaches adesired position, the steering mechanism is removed and the deliverysystem is directed into the passage along the guide wire. Otherprocedures for directing catheters or similar devices into largerpassages of the body, such as the esophagus, are also well known.

In some cases, it is desirable to dilate the body passage prior todeploying a stent in the passage, especially in the case of a stricturein the passage. In such a case, a balloon catheter is directed into thepassage along the guide wire and the balloon is inflated to dilate thestricture in the body passage.

Thus, use of a conventional delivery system for a self-expanding stentin combination with a guide wire, a pre-deployment dilatation balloon,and a post-deployment expandable balloon, would require the followingtime-consuming procedures: delivery of the guide wire; delivery andactivation of the pre-deployment balloon to dilate the passage; removalof the pre-deployment balloon; delivery of the stent deployment systemand deployment of the stent; removal of the stent delivery system;delivery and activation of an expandable balloon device to assist inexpansion of the stent; and removal of the expandable balloon device andguide wire. The repeated insertion and removal of delivery systems iscumbersome, prolongs the procedure, increases the trauma and risk to thepatient, and increases costs.

SUMMARY OF THE INVENTION

To overcome the disadvantages of the prior art, and in accordance withthe purposes of the invention, as embodied and broadly described herein,there is provided a dilatation and stent delivery system that includes adilatation catheter having an expandable member on a distal end, and astent delivery catheter configured to retain a stent and deliver thestent to a body passage. The stent delivery catheter defines a lumensized to receive the dilatation catheter and permit movement of thedilatation catheter relative to the stent delivery catheter.

According to an embodiment, the stent delivery catheter includes alocking mechanism at a proximal end for selectively restricting movementof at least a portion of the stent delivery catheter relative to thedilatation catheter.

According to other embodiments, the stent delivery catheter includes anouter sheath, an inner shaft sized to be received in a lumen of theouter sheath, and a locking mechanism fixed to a proximal end of theinner shaft for selectively restricting movement of the inner shaftrelative to the dilatation catheter. The locking mechanism is configuredto selectively engage the dilatation catheter. The locking mechanismattaches to a proximal end of a handle at a proximal end of the innershaft. The inner shaft terminates in the handle, and the lockingmechanism defines a lumen to receive the dilatation catheter. Accordingto further embodiments, the inner shaft includes a stent holder spacedfrom a distal end of the inner shaft and configured to retain the stent,the outer sheath moves relative to the inner shaft, and a first handleis at a proximal end of the outer sheath and a second handle is at theproximal end of the inner shaft.

According to still further embodiments, the expandable member is aballoon. The balloon may expand to a plurality of distinct diameterscorresponding to known inflation pressures.

According to even further embodiments, the dilatation catheter definesan inflation lumen for passing inflation fluid to the expandable memberand a guide wire lumen for accommodating a guide wire. A length of thedilatation catheter may be greater than a length of the stent deliverycatheter.

According to other embodiments of the invention, the stent deliverycatheter includes an outer sheath and an inner shaft sized to bereceived in a lumen of the outer sheath. A guide wire, hypotube, coil,or other like-structure may be placed within a lumen of the inner shaftand include a distal tip having a cross-sectional size at least as largeas a cross-sectional size of the outer sheath.

Further embodiments include a second expandable member at a distal endof the dilatation and stent delivery system. The second expandablemember may be located on a distal end of the stent delivery catheter oron a separate dilatation catheter. The expandable member of thedilatation catheter expands to a first diameter, the second expandablemember expands to a second diameter, and the second diameter is largerthan the first diameter.

According to another aspect, the invention includes a combination of astent and a dilatation and stent delivery system. The stent may be aself-expanding stent.

According to a further aspect, the invention includes a method forimplantation of a stent. The method includes delivering a stent deliverycatheter proximate to a treatment site in a body passage, the stentdelivery catheter retaining the stent; delivering a dilatation catheterproximate to the treatment site in the body passage, the dilatationcatheter having an expandable member on a distal end; implanting thestent at the treatment site, while at least a portion of the dilatationcatheter is positioned within a lumen of the stent delivery catheter;and expanding the expandable member to assist in expansion of the stent.According to an embodiment, the method further includes expanding theexpandable member to dilate the treatment site of the body passage priorto implanting the stent. According to another embodiment, the stent isimplanted while the dilatation catheter is positioned proximate thetreatment site.

According to other embodiments, the expandable member is expanded todilate the treatment site, while the stent delivery catheter isproximate the treatment site and while at least a portion of thedilatation catheter is positioned within the lumen of the stent deliverycatheter. The expandable member may be expanded to assist in expansionof the stent, while the stent delivery catheter is proximate thetreatment site and while at least a portion of the dilatation catheteris positioned within the lumen of the stent delivery catheter.

According to further embodiments, the dilatation catheter is deliveredproximate to the treatment site at the same time as the stent deliverycatheter is delivered proximate to the treatment site, the dilatationcatheter reaches the treatment site prior to the stent delivery catheterreaching the treatment site, or the dilatation catheter is deliveredproximate to the treatment site after delivery of the stent deliverycatheter proximate to the treatment site.

According to still further embodiments, the method includes exposing theexpandable member beyond a distal end of the stent delivery catheterprior to expanding the expandable member to dilate the treatment site ofthe body passage, and withdrawing the expandable member into the distalend of the stent delivery catheter prior to the stent implanting stepand/or moving the distal end of the stent delivery catheter over theexpandable member prior to the stent implanting step. The method alsomay include exposing the expandable member beyond a distal end of thestent delivery catheter prior to expanding the expandable member toassist in expansion of the stent.

According to additional embodiments, the method further includesrestricting movement of the dilatation catheter relative to at least aportion of the stent delivery catheter. The stent delivery catheterincludes an outer sheath, an inner shaft sized to be received in a lumenof the outer sheath, and a locking mechanism fixed to a proximal end ofthe inner shaft, and the restricting step includes actuating the lockingmechanism to restrict movement of the inner shaft relative to thedilatation catheter. The restricting step may occur during theimplanting step.

According to another embodiment, the step of expanding the expandablemember to dilate the treatment site is performed prior to delivering thestent delivery catheter to the treatment site.

According to embodiments, the dilatation catheter includes a dilatationshaft and the expandable member is a balloon mounted on a distal end ofthe dilatation shaft, the stent delivery catheter includes an outersheath and an inner shaft sized to be received in the outer sheath, andthe inner shaft defines a lumen sized to receive the dilatation shaftand permit movement of the dilatation shaft relative to the stentdelivery catheter. The expandable member may be inflatable.

According to further embodiments, the method further includes expandinga second expandable member to expand an end of the stent. The secondexpandable member may be located on a distal end of the stent deliverycatheter. The expandable member on the distal end of the dilatationcatheter is expanded to a first diameter and the second expandablemember is expanded to a second diameter larger than the first diameter.The method may include expanding a second expandable member to expandonly a portion of the stent.

According to another aspect of the invention, a method for implantationof a stent includes delivering a stent delivery catheter proximate to atreatment site in a body passage, the stent delivery catheter retainingthe stent; delivering a dilatation catheter proximate to the treatmentsite in the body passage, the dilatation catheter having an expandablemember on a distal end; implanting the stent at the treatment site,while movement of the dilatation catheter is restricted relative to atleast a portion of the stent delivery catheter; and expanding theexpandable member to assist in expansion of the stent.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute partof the specification, illustrate presently preferred embodiments of theinvention and, together with the general description given above anddetailed description of the preferred embodiments given below, serve toexplain the principles of the invention.

FIG. 1 is a cross-sectional view of an embodiment of a dilatation anddelivery system according to the invention;

FIG. 2 is a cross-sectional view of an embodiment of a stent deliverycatheter of the delivery system of FIG. 1;

FIG. 3 is a plan view of an embodiment of a dilatation catheter of thedelivery system of FIG. 1;

FIG. 4 is a cross-sectional view of the delivery system of FIG. 1, withan outer sheath retracted relative to an inner shaft to release a stent,according to an embodiment;

FIG. 5 is a cross-sectional view of another embodiment of a dilatationand delivery system according to the invention;

FIG. 6 is a cross-sectional view of a further embodiment of a dilatationand delivery system according to the invention;

FIG. 7 is a cross-sectional view of a still further embodiment of adilatation and delivery system according to the invention;

FIG. 8A is a top view of a lock portion of an embodiment of a lockadapter used in dilatation and delivery systems according to theinvention;

FIGS. 8B and 8C are respectively a top view and a side cross-sectionalview of an embodiment of a lock adapter used in dilatation and deliverysystems according to the invention;

FIG. 9 is an exploded cross-sectional view of the lock adapter of FIGS.8B and 8C; and

FIG. 10 is a plan view of an alternative embodiment of a dilatationcatheter for use in a system according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference now will be made in detail to the present preferredembodiments of the invention, examples of which are illustrated in theaccompanying drawings, in which like numerals designate like elements.

The present invention relates to a system for a less cumbersome, lesstime-consuming, and safer method for dilating a passageway in a body andimplanting a stent in the passageway. According to embodiments to bedescribed, the system includes a dilatation device having an expandablemember, such as a balloon, on a distal end, and a stent delivery devicethat retains a stent and has a lumen that accommodates the dilatationdevice. The dilatation device may be moved independent of the stentdelivery device. A locking mechanism may be provided at the proximal endto restrict movement of the dilatation device relative to at least aportion of the stent delivery device during suitable stages of theprocedure, such as during stent implantation.

The dilatation and stent delivery devices may be delivered over a guidewire and may be delivered proximate to the treatment site eithertogether or separately. Once delivered to the site, the dilatation andstent delivery devices each may remain proximate to the treatment siteduring the entire procedure, i.e. the dilatation device may remainproximate the site as the stent is delivered, and the stent deliverydevice may remain proximate the site during pre-dilatation of thepassage and/or balloon assisted expansion of the stent. The dilatationand stent delivery devices therefore do not need to be removed duringthe procedure, decreasing the steps and time required of the procedureand the trauma to the patient.

The system and method of the present invention is suitable for use inany passageway of a body, including gastrointestinal passages, bloodvessels, or other body lumens. The system and method may be applied inendoscopic procedures, such as procedures involving esophageal, biliary,pulmonary, urology, and colon stricture management.

FIG. 1 shows a dilatation and stent delivery system 10 according to anembodiment of the present invention. System 10 includes a stent deliverydevice, or catheter, 12 and a dilatation device, or catheter, 14.Catheters 12 and 14 are shown separately in FIGS. 2 and 3, respectively.

With reference to FIG. 2, stent delivery catheter 12 includes an outermember, or sheath, 16 and an inner member, or shaft, 18. Preferably,sheath 16 and shaft 18 are tubular shaped and relatively flexible totraverse tortuous anatomy. Sheath 16 defines an inner lumen thataccommodates shaft 18 and through which shaft 18 moves axially relativeto sheath 16. In a preferred embodiment, sheath 16 has an outer diameterof approximately 2.5-20 mm. Shaft 18 also defines a lumen 20 thereinthat has a size sufficient to accommodate dilatation catheter 14 orother devices, such as other dilatation devices, guide devices, or othertherapeutic or diagnostic devices, as desired. Catheter 14 moves axiallythrough lumen 20 relative to shaft 18 and sheath 16. In a preferredembodiment, shaft 18 has an outer diameter of approximately 2-19 mm anddefines a lumen 20 having a diameter of approximately 1-18 mm.

Preferably, a length of dilatation catheter 14 is greater than a lengthof stent delivery catheter 12. For example, for an operation within theesophagus of a patient, dilatation catheter 14 may have a length ofabout 140 cm to about 200 cm, and stent delivery catheter may have alength of about 100 cm to about 130 cm. Other catheter lengths arewithin the scope of the invention.

A distal tip 22 connects to the distal end of shaft 18. Tip 22 istapered and has a conical shape. Tip 22 is made of a material that willnot damage tissue as stent delivery catheter 12 inserts and travelsthrough a body passage. Tip 22 has a reduced diameter proximal portion23, as most clearly shown in FIG. 4, that receives the distal end ofsheath 16 and acts as a seat for sheath 16 when sheath 16 is in itsdistal most position relative to shaft 18. In this embodiment, thediameter of tip 22 at its largest point approximates the outer diameterof sheath 16.

At its proximal end, stent delivery catheter 12 includes an inner sheathhandle 26 that is fixedly connected to the proximal end of shaft 18.Catheter 12 also includes a handle 24 fixedly connected to the proximalend of outer sheath 16. Each of handles 24,26 may be any suitable handleknown in the art for moving inner shaft 18 and outer sheath 16 relativeto one another.

Handle 26 includes a lock mechanism, or adapter, 28 for releasablylocking dilatation catheter 14 relative to inner shaft 18, as will bedescribed in more detail below. Lock adapter 28 selectively restrictsmovement of at least a portion of stent delivery catheter 12 relative todilatation catheter 14. More specifically, lock adapter 28 selectivelyengages shaft 40 and thereby restricts movement of shaft 40 relative toinner shaft 18.

Lock adapter 28 is fixed to a proximal end of handle 26 and defines alumen to receive dilatation catheter 14. An embodiment of lock adapter28 is shown in FIGS. 8A-8C and 9. Lock adapter 28 includes a lockportion 400 and a luer adapter 402. A distal nose portion 404 of lockportion 400 frictionally fits within a proximal end 406 of adapter 402.An internally-threaded distal end 408 of adapter 402 engages theproximal end of handle 26 to connect lock adapter 28 to handle 26.Alternatively, a locking mechanism may be incorporated into the proximalhandle.

As shown in FIGS. 8C and 9, lock portion 400 includes five parts: abutton 410; a pressure member 412; a tube 414; a tube holder 416; and amain casing 418 that receives the other four parts. Main casing definesa central, longitudinal lumen 420 that accommodates tube 414 and tubeholder 416. A distal end 414 b of tube 414 rests against an angled stopsurface 422 of casing 418. A proximal end 414 a of tube 414 receives adistal extension 424 of tube holder 416. A proximal portion 426 of tubeholder 416 has an outer diameter closely matching the inner diameter atthe proximal end of lumen 420 of casing 418, so that holder 416frictionally fits within casing 418. The proximal end 414 a of tube 414rests against a stop 428 formed between extension 424 and portion 426. Alumen 430 of holder 416, a lumen 432 of tube 414, and lumen 420 ofcasing 418 are configured to receive a medical device, such as a guidewire, balloon catheter, or any other desired device.

Button 410 has a raised finger trigger 440 on a top surface. Casing 418includes suitable structure, such as groves; to receive complementarystructure on a bottom of button 410, such as ridges, to permit button410 to slide longitudinally along casing 418. Lock adapter 28 is alinear locking system in that, pressing finger trigger 440 forward by auser's thumb, for example, sets lock adapter 28 in the “on,” or locked,position. Stop 441 of casing 418 limits forward movement of button 410.Movement of finger trigger 440 in the proximal direction sets lockadapter 28 in the “off,” or unlocked position.

Button 410 includes a ramped undersurface 442 which slides against thetop of pressure member 412. Member 412 rests between undersurface 442and tube 414 within a passage 444 of casing 418. Tbe 414, and optionallymember 412, is preferably made of a resilient material so that, asbutton 410 is moved forward (i.e., distally), the pressing ofundersurface 442 against member 412 forces member 412 against tube 414.This causes a portion of tube 414 to deflect inwardly and against amedical device (such as dilatation catheter 14), thus locking themedical device relative to lock adapter 28.

Any other structure associated with stent delivery catheter 12 ordilatation catheter 14 that is suitable for restricting movement of allor portions of the catheters relative to one another may be used. Forexample, various commercially available locking mechanisms may be used,including a male touhy borst with a spin lock available from Qosina(Part No. 80345).

A stent holder 30 is located on an outer surface of shaft 18 near itsdistal end, as shown in FIG. 4. Stent holder 30 may be a holding sleevecoaxially mounted about the inner shaft 18 and sized and configured suchthat a self-expanding stent can be placed around it. The holding sleevecan retain the positioning of the stent during delivery by cooperatingwith the outer sheath 16 to prevent axial movement of the stent. In thisway, the stent may be reconstrained during delivery if necessarybecause, for example, initial stent placement is not accurate.

Stents suitable for use in combination with this invention includebioabsorbable and/or polymer stents, such as stents made ofbioabsorbable poly-1-lactide filaments braided in a tubular meshconfiguration. Stents made of nitinol, stents with coverings to resisttissue ingrowth for example, and any other suitable, biocompatible stentalso may be used. One or both ends of the stent may be flared uponexpansion to assist in anchoring the stent in place. The invention inits broadest sense is not limited by the shape, size, composition, ortype of the self-expanding stent. Moreover, the invention includes inits broadest sense expandable stents, such as balloon-expandable stents.

With reference to FIG. 3, dilatation catheter 14 includes an elongatemember, or shaft, 40 that is preferably tubular and relatively flexibleto traverse tortuous anatomy. Shaft 40 preferably includes two lumens toaccommodate the guide wire and inflation media. A first lumencommunicates with a port 46 that accepts a guide wire 60. A second lumencommunicates with a port 48 to receive and pass inflation fluid from theproximal end to an inflation device 42 at the distal end. Port 48connects to any suitable inflation device known in the art, such as asyringe. The inflation medium may be any suitable fluid known in theart, such as air, saline, or a radiographic dye suitable for endoscopicvisualization. Ports 46, 48 may be luer adapters or any other suitablelike device known in the art. Tubes 47, 49 are affixed to andcommunicate with ports 46, 48 and lead to the guide wire lumen andinflation lumen, respectively. A connector 50 provides the connection ofports 46, 48 to the remainder of dilatation catheter shaft 40. Connector50 is a molded Y-connector. Any other suitable connector known in theart may be used. Shaft 40 also includes an atraumatic distal tip 44 thatincludes a lumen therein and a hole at its distal end, permittingpassage of guide wire 60 through the distal end of dilatation catheter14. When catheters 12 and 14 are in their relative positions as shown inFIG. 1, tip 44 provides a reduction in the profile of the tip sectionfrom the profile of tip 22. It is contemplated that embodiments ofcatheter 12 will not include a distal tip 22, in which case distal tip44 exposed from the distal end of catheter 12 creates the atraumaticdistal tip for the system.

Inflation device 42 is preferably a balloon coaxially mounted aboutshaft 40. A port or hole in shaft 40 (not shown in the Figures) willpermit inflation fluid to pass from the inflation lumen of shaft 40 toballoon 42. In an embodiment, balloon 42 may be inflatable to aplurality of distinct, pressure-controlled diameters. Such a multi-stagedilatation catheter is sold commercially by Boston ScientificCorporation under the name CRE™ Wireguided Balloon Dilator. The CRE™Wireguided Balloon Dilator includes a balloon that is inflatable tothree distinct diameters at three separate pressures, with little or nowaisting of the balloon and with a high degree of radial force at anygiven pressure. For example, at pressures of 3, 5, and 8 atmospheres,the balloon increases to diameters of 10, 11, and 12 mm, respectively.Other balloon dilatation catheters may be used, including those withballoons that do not inflate to distinct diameters at known pressures.

FIG. 1 shows shaft 40 of dilatation catheter 14 inserted within lumen 20of stent delivery catheter 12. In FIG. 1, outer sheath 16 is in itsdistal most position relative to inner shaft 18, and substantially allof balloon 42 is within lumen 20 of catheter 12. Atraumatic tip 44 isexposed from the distal end of catheter 12. This relative positioning ofcatheters 12 and 14, and sheath 16 and shaft 18, is suitable forinserting delivery system 10 over guide wire 60 and passing system 10through a patient's tortuous anatomy to a site of interest in, forexample, an esophagus. In this position, lock adapter 28 may be actuatedto engage shaft 40 to restrict movement of shaft 40 relative to shaft18. As alternatives to inserting catheters 12 and 14 together in thelocked, relative positions shown in FIG. 1, and as will be described,catheters 12 and 14 may be inserted separately to the treatment site,inserted together in different relative positions, for example withballoon 42 extending from the distal end of delivery catheter 12, orinserted together without actuating lock adapter 28 to restrict relativemovement.

The invention includes a method for dilatation and for delivery of astent that uses a delivery system having a stent delivery catheter and adilatation catheter. According to an embodiment of the invention, thedelivery system is passed along a conventional guide wire to the area ofthe anatomical passage to be treated. In other embodiments, the deliverysystem may be passed through an endoscope or along an endoscope to thetreatment site.

In embodiments using a guide wire, once a guide wire has been insertedinto the patient and traversed an anatomical passage to the area to betreated through any known, conventional method, delivery system 10 maybe inserted over the wire to the treatment site. This may beaccomplished in a number of ways. For example, the user may first insertstent delivery catheter 12 over the wire to the treatment site, followedby dilatation catheter 14 over the wire and through stent deliverycatheter 12. As an alternative, stent delivery catheter 12 anddilatation device 14 may be inserted together as a unit in theirrelative positions shown in FIG. 1. Inserting the catheters togetheradvantageously lessens the number of steps in the procedure. Duringinsertion, lock adapter 28 may be actuated to restrict relative movementof the catheters. Adapter 28 may restrict movement during insertion withtip 44 exposed from the end of catheter 12, as shown in FIG. 1. As aneven further alternative, catheters 12 and 14 may be inserted togetherin relative positions different than that shown in FIG. 1, for examplewith balloon 42 extending from the distal end of delivery catheter 12,in a locked or unlocked state.

Once delivery system 10 is positioned proximate the treatment site,dilatation catheter 14 is extended distally relative to stent deliverycatheter 12 to expose balloon 42 from the distal end of catheter 12. Todo so, the user first must ensure that lock adapter 28 is in theunlocked position so that shaft 40 may move axially relative to shaft18. Then, the user either pushes catheter 14 distally or pulls catheter12 proximally until balloon 42 is exposed. The user then positionsballoon 42 in the body passage at the site to be dilated.

Suitable visualization techniques known to those skilled in the art maybe used to aid in positioning catheters 12 and 14 and their components.For example, radiopaque markers may be fixed at appropriate positionsalong the delivery system 10 and fluoroscopic visualization may be used.As another example, one or both catheters may be made radiopaque bymixing a radiopaque compound such as tungsten or barium sulfate to thepolymer from which the catheter is manufactured.

Once balloon 42 is positioned, suitable inflation media is insertedthrough a lumen of dilatation catheter 14 to balloon 42 to inflateballoon and dilate the treatment site. If a multi-stage dilatationcatheter such as a CRE™ Wireguided Balloon Dilator is used, the balloonmay be inflated to a distinct diameter at a known pressure. In certainembodiments of the method, the treatment site may not require dilatationprior to stent deployment.

After suitable dilatation of the passage, if such dilatation is requiredor desired, the user deflates balloon 42 and moves dilatation catheter14 in a proximal direction relative to delivery catheter 12, by eitherpulling catheter 14 into catheter 12 or pushing catheter 12 overcatheter 14. This position is shown in FIG. 1. The user then may placelock adapter 28 in the locked position so that shaft 40 is fixedrelative to shaft 18.

The user then may reposition delivery system 10 as needed, for stentholder 30 and its held stent to be positioned at the treatment site. Theuser may either retract balloon 42 into catheter 12, advance catheter 12over balloon 42, or leave balloon 42 exposed. Once again, suchpositioning may be performed through any suitable visualizationtechniques known to those skilled in the art.

Once the stent is in its proper position, the user pulls on handle 24 toretract sheath 16 relative to shaft 18, until stent holder 30 and itsheld stent are exposed. This will release the stent and allow the stentto self-expand within the body passage. The user thereafter may movehandle 24 distally to reposition sheath 16 in the position shown in FIG.1, or retract handle 26 to avoid the possibility that handle 24 willcontact the delivered stent.

If additional expansion of the stent is needed, the user then mayreposition system 10 so that balloon 42 is positioned within the stent.If balloon 42 is not already exposed from the distal end of catheter 12,the user unlocks lock adapter 28 so that shaft 40 may move relative toshaft 18. The user then retracts stent delivery catheter 12 relative todilatation catheter 14 by pulling catheter 12 in the proximal direction.The user retracts catheter 12 until balloon 42 is exposed at the distalend. Suitable inflation media then is inserted through a lumen ofdilatation catheter 14 to balloon 42 to inflate balloon 42 and assist inexpanding the stent and further dilating the body passage. If amulti-stage dilatation catheter such as a CRE™ Wireguided BalloonDilator is used, the balloon may be inflated to a distinct diameter at aknown pressure.

Once the stent is expanded to the desired diameter, balloon 42 may bedeflated and, if desired, repositioned within an end of the stent toexpand a flare at that end. Once balloon is properly positioned,suitable inflation media then is inserted through a lumen of dilatationcatheter 14 to balloon 42 to inflate balloon 42 and expand the flaredstent end. If a multi-stage dilatation catheter such as a CRE™Wireguided Balloon Dilator is used, the balloon may be inflated to adistinct diameter at a known pressure.

Once the stent end is expanded, balloon 42 may be deflated. The userthen may remove delivery system 10, including stent delivery catheter 12and dilatation catheter 14, and guide wire 60 from the patient's body.

FIG. 5 shows a stent delivery system 100 according to another embodimentof the present invention. This embodiment differs from that shown inFIGS. 1-4 primarily in the placement of a distal tip relative to thedelivery system. The reference numerals used in connection with FIGS.1-4 designate like elements in the embodiment shown in FIG. 5. In thisembodiment, a distal tip 122 is fixedly connected at its proximal end toa distal end of a hypotube 124. As an alternative to the arrangementshown in FIG. 5, hypotube 124 may be a coil for increased flexibility.The coil may be metal and also may include a biocompatible covering.Hypotube 124 extends through and may move relative to a lumen ofdilatation catheter 14. Hypotube 124 has a length greater than that ofdilatation catheter and has a proximal end that extends out of theproximal end of dilatation catheter 14. Distal tip 122 may bemanipulated by a user at that proximal end of tube 124. At least aportion of distal tip 122 has a cross-sectional size at least as largeas a cross-sectional size of outer sheath 16. Distal tip 122 thereforecan stop forward relative movement of sheath 16. A guide wire 60 mayextend through the lumen of hypotube 124 and a central lumen of distaltip 122, as shown in FIG. 5.

The embodiment of delivery system 100 shown in FIG. 5 is used in asimilar fashion as that described in connection with the embodiment ofFIGS. 1-4. The main differences include delivery of hypotube 124 overwire 60 once wire 60 reaches a treatment site. Distal tip 122 preferablyextends distally of the treatment site so that balloon 42 and stentholder 30 may reach the site. Catheters 12 and 14 may be inserted withhypotube 124 over wire 60, or catheters 12 and 14 may be inserted overhypotube 124 after hypotube 124 reaches a treatment site. The remainingmethod steps when using system 100 are the same as or substantially thesame as the steps described above in connection with other embodiments.

FIG. 6 shows a stent delivery system 200 according to another embodimentof the present invention. This embodiment differs from that shown inFIGS. 1-4 and 5 primarily in the placement of a distal tip relative tothe delivery system. The reference numerals used in connection withFIGS. 1-4 and 5 designate like elements in the embodiment shown in FIG.6. In this embodiment, a distal tip 222 is directly connected at itsproximal end to the tip of the dilatation catheter. At least a portionof distal tip 222 has a cross-sectional size at least as large as across-sectional size of outer sheath 16 to stop forward relativemovement of sheath 16. Distal tip 222 has a central lumen to accept aguide wire 60 that moves relative to tip 222. The embodiment of deliverysystem 200 shown in FIG. 6 is used in a similar fashion as thatdescribed in connection with the embodiment shown in FIGS. 1-4.

In a further embodiment of the present invention, a second expandablemember, or balloon, may be incorporated into the system. In oneembodiment, the additional balloon may be placed on the stent deliverycatheter, preferably distal to the stent holder. The additional balloonmay have different characteristics than the dilatation balloon, forexample expandable to a different and larger diameter. The additionalballoon may be used, for example, to expand the ends of a flared stent.

FIG. 7 shows an embodiment of a dilatation and delivery system 300 thatincorporates a second expandable member. The reference numerals used inconnection with the above-described Figures designate like elements inthe embodiment shown in FIG. 7. The differences of the FIG. 7 embodimentwill be described. The second expandable member is a balloon 342 onstent delivery catheter 12, and specifically inner shaft 18. Balloon 342is positioned distal to stent holder 30. In this embodiment, balloon 342expands to a larger diameter than balloon 42, as shown in FIG. 7.

At the proximal end of the delivery system 300, handle 26 that attachesto inner shaft 18 includes a side passage that receives a tube 347. Tube347 has a port 346 at its proximal end. Port 346 is configured toconnect to any suitable inflation source (not shown) to supply inflationmedia through inner shaft 18 to balloon 342.

Balloon 342 may be used, for example, to expand the ends of a flaredstent at areas where no stricture exists. After balloon 42 aids inexpansion of the stent to the desired diameter under a stricture andballoon 42 subsequently is deflated, balloon 342 may be positionedwithin an end of the stent to expand a flare at that end. Once balloon342 is properly positioned, suitable inflation media is inserted throughport 346, tube 347, and a lumen of inner shaft 18 to balloon 342 toinflate balloon 342 and expand the flared stent end. Each end of a stentmay be flared in this way.

Also at its proximal end, delivery system 300 includes a second lockadapter 328 for restricting movement of guide wire 60 relative todilatation catheter 14. Such a lock adapter may be used in the systemsdescribed above as well. Lock adapter 328 may include the same orsimilar structural components as the lock adapter shown and described inconnection with FIGS. 8A-8C and 9, and therefore operate in a likefashion. Alternatively, lock adapter 328 may be any suitable lockingmechanism known in the art.

As an alternative embodiment to the system shown in FIG. 7, anadditional balloon may be placed on the dilatation catheter. Thisembodiment is shown FIG. 10. Dilatation catheter 14 a includes a balloon442 proximate dilatation balloon 42 and proximal to balloon 42. As analternative, balloon 442 could be distal to balloon 42. With thisarrangement, an additional inflation port 446 and tube 447 correspondingto balloon 442 connects at the proximal end of catheter 14 a toconnector 50. Inflation media may be supplied through port 446 andthrough an additional lumen (not shown) of catheter 14 a to balloon 442.

Balloon 442 may be used, for example, to expand the ends of a flaredstent at areas where no stricture exists. After balloon 42 aids inexpansion of the stent to the desired diameter under a stricture andballoon 42 subsequently is deflated, balloon 442 may be positionedwithin an end of the stent to expand a flare at that end. Once balloon442 is properly positioned, suitable inflation media is inserted throughport 446, tube 447, and a lumen of inner shaft 18 to balloon 442 toinflate balloon 442 and expand the flared stent end. Each end of a stentmay be flared in this way.

While this invention has been described with specific embodimentsthereof, it is evident that many alternatives, modifications, andvariations will be apparent to those skilled in the art. Accordingly,the preferred embodiments of the invention as set forth herein areintended to be illustrative, not limiting. Various changes may be madewithout departing from the spirit and scope of the invention.

1. A dilatation and stent delivery system, the system comprising: adilatation catheter, the dilatation catheter having an expandablemember; and a stent delivery catheter, the stent delivery cathetercomprising: an inner shaft, the inner shaft comprising a stent retainingregion, the inner shaft defining a lumen sized to receive the dilatationcatheter and to permit movement of the dilatation catheter relative tothe stent delivery catheter, an outer sheath, the outer sheath having anon-retracted state and a retracted state, the outer sheath comprising adistal end, the distal end of sheath being disposed over the stentretaining region of the inner shaft when the outer sheath is in thenon-retracted state, the distal end of the outer sheath being proximalto the stent retaining region when the outer sheath is in the retractedstate.
 2. The system of claim 1, wherein the stent delivery catheterincludes a locking mechanism at a proximal end for selectivelyrestricting movement of at least a portion of the stent deliverycatheter relative to the dilatation catheter.
 3. The system of claim 1,wherein the stent delivery catheter further includes a locking mechanismfixed to a proximal end of the inner shaft for selectively restrictingmovement of the inner shaft relative to the dilatation catheter.
 4. Thesystem of claim 3, wherein the locking mechanism is configured toselectively engage the dilatation catheter.
 5. The system of claim 3,further comprising a handle at a proximal end of the inner shaft,wherein the locking mechanism is attached to a proximal end of thehandle.
 6. The system of claim 5, wherein the inner shaft terminates inthe handle, and the locking mechanism defines a lumen to receive thedilatation catheter.
 7. The system of claim 3, the stent deliverycatheter further comprising a stent holder configured to retain a stenton the stent retaining region of the inner shaft.
 8. The system of claim3, further comprising a first handle at a proximal end of the outersheath and a second handle at the proximal end of the inner shaft. 9.The system of claim 1, wherein the expandable member is a balloon. 10.The system of claim 9, wherein the balloon expands to a plurality ofdistinct diameters corresponding to known inflation pressures.
 11. Thesystem of claim 1, wherein the dilatation catheter defines an inflationlumen for passing inflation fluid to the expandable member and a guidewire lumen for accommodating a guide wire.
 12. The system of claim 1,wherein a length of the dilatation catheter is greater than a length ofthe stent delivery catheter.
 13. The system of claim 1, wherein thedilatation catheter includes a distal tip a portion of which has across-sectional size at least as large as a cross-sectional size of theouter sheath.
 14. The system of claim 1, further comprising a secondexpandable member at a distal end of the dilatation and stent deliverysystem.
 15. The system of claim 14, wherein the second expandable memberis located on a distal end of the stent delivery catheter.
 16. Thesystem of claim 14, wherein the second expandable member is located onthe distal end of the dilatation catheter.
 17. The system of claim 14,wherein the expandable member of the dilatation catheter expands to afirst diameter, the second expandable member expands to a seconddiameter, and the second diameter is larger than the first diameter. 18.The system of claim 1, wherein the stent delivery catheter furthercomprises a stent holder configured to retain a stent on the stentretaining region of the inner shaft.
 19. The system of claim 1, furthercomprising a stent disposed about the stent retaining region of theinner shaft.
 20. The system of claim 1, wherein a distal end of theinner shaft is not fixedly coupled to the outer sheath.
 21. The systemof claim 1, wherein the inner shaft is extendable from and retractableinto a distal end of the lumen of the outer sheath.
 22. The system ofclaim 21, wherein the stent delivery catheter further includes a distaltip, the distal tip including a reduced diameter proximal portion forreceiving a distal portion of the outer sheath and thereby acting as aseat when the outer sheath is in its distal most position relative tothe inner shaft.
 23. The system of claim 1, wherein the expandablemember is capable of expanding to a plurality of distinct maximumdiameters corresponding to known inflation pressures.
 24. The system ofclaim 1, wherein the inner shaft is configured to slide along an innersurface of the outer sheath.
 25. In combination, a stent and adilatation and stent delivery system, the combination comprising: astent; a dilatation catheter, the dilatation catheter having a balloon;and a stent delivery catheter, the stent delivery catheter comprising:an inner shaft, the inner shaft comprising a stent retaining region, thestent disposed about the stent retaining region; and a tip, the tipbeing tubular and engaged to a distal end of the inner shaft; the innershaft and tip defining a lumen sized to receive the dilatation catheterand permit movement of the dilatation catheter relative to the stentdelivery catheter.
 26. The combination of claim 25, wherein the stent isa self-expanding stent.
 27. The combination of claim 25, wherein thestent delivery catheter further comprises a sheath, the sheath having anon-retracted state and a retracted state, the sheath comprising adistal end, the distal end of the sheath being disposed on a proximalend of the tip and over the stent when the sheath is in thenon-retracted state, and the distal end of the sheath being proximal tothe stent retaining region when the sheath is in the retracted state.